From what I understood, he was depressed, went to the hot springs, Elizabeth happened to come there too (no idea how). 
He even tries to hide himself underwater, to stay out of her vision 
She Then started ranting about how he left/ abandoned her... he was supposed to protect her tho
And then he (foolishly, if I might add) exposes himself with a LOUD apology! 



He then proposes to take a knighthood oath for her (or something alike, idk)
And she gives him her hand (which he kisses) and the oath is complete 
She 
 then  points out that they are both nude 
And he 
 then  gets embarrassed 


